Process of assembling and repositioning two parts

Abstract

The invention relates to a process for assembling and repositioning at least two parts by means of a repositionable hot melt adhesive, wherein said parts are held together in assembled position when said adhesive is at a temperature TA and can be repositioned in relation to one another when said adhesive is heated to a temperature TC, wherein said adhesive comprises at least a formulation, which:at the temperature TC has the form of a mixture of polymer chains comprising at least pendant diene units X and of coupling molecules comprising at least two dienophile end groups Y, wherein said X units and said Y groups are arranged to be able to react with one another and to bond together by means of the Diels-Alder reaction at a temperature TDA and to be able to regenerate by means of the retro-Diels-Alder reaction at a temperature TRDA,at a temperature TA has the form of a three-dimensional network, in which the polymer chains are linked to one another by the coupling molecules by means of the Diels-Alder reaction,where TA<TRDA≤TC, where TDA ranges between 0° C. and 100° C. and TRDA ranges between 50° C. and 200° C., and TDA is strictly lower than TRDA.The polymer chain is a block copolymer comprising at least a first polymer block having a glass transition temperature Tg or a melting temperature Tf ranging between 40° C. and 200° C., and at least a second polymer block comprising at least pendant diene units X and having a glass transition temperature Tg or a melting temperature Tf lower than TDA.

Description

[0001]This application claims priority from European Patent application 15201237.3 of Dec. 18, 2015, the entire disclosure of which is hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a process for assembling and repositioning two parts by means of a repositionable hot melt adhesive arranged to assemble said parts together and to allow the parts to be repositioned when said adhesive is heated.BACKGROUND OF THE INVENTION[0003]In the field of clock-making timepiece parts are assembled together by means of a glue or an adhesive. The gluing points must be formed by means of a repositionable hot melt adhesive to enable them to be reworked using heat in a manual operation and to allow the glued parts to be repositioned in an optimum manner either during assembly or during maintenance or repair of the parts as part of aftersales service. Moreover, this adhesive must also have resistance to chemical cleaning operations, in particular to wi...

AI Technical Summary

Benefits of technology

The invention provides a process to create an assembly of parts that canbe reworked using heat and still resistant to chemical cleaning operations. This is possible because the blocks in the assembly have their own glass transition temperature or melting temperature, which allows the adhesive to have two properties: quick positioning / immobilization and resistance to chemical cleaning operations.

Problems solved by technology

Parts assembled using shellac therefore have a poor resistance to timepiece cleaning operations.

However, they cannot be reworked using heat, and therefore parts assembled using thermosetting glues cannot be separated and repositioned if required.

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